/* * Portions Copyright (c) 2003 Century Software, Inc.   All Rights Reserved. * * This file is part of the PIXIL Operating Environment * * The use, copying and distribution of this file is governed by one * of two licenses, the PIXIL Commercial License, or the GNU General * Public License, version 2. * * Licensees holding a valid PIXIL Commercial License may use this file * in accordance with the PIXIL Commercial License Agreement provided * with the Software. Others are governed under the terms of the GNU * General Public License version 2. * * This file may be distributed and/or modified under the terms of the * GNU General Public License version 2 as published by the Free * Software Foundation and appearing in the file LICENSE.GPL included * in the packaging of this file. * * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING * THE WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A * PARTICULAR PURPOSE. * * RESTRICTED RIGHTS LEGEND * * Use, duplication, or disclosure by the government is subject to * restriction as set forth in paragraph (b)(3)(b) of the Rights in * Technical Data and Computer Software clause in DAR 7-104.9(a). * * See http://www.pixil.org/gpl/ for GPL licensing * information. * * See http://www.pixil.org/license.html or * email cetsales@centurysoftware.com for information about the PIXIL * Commercial License Agreement, or if any conditions of this licensing * are not clear to you. *//* This code is originally derived from Sunclock 3.xx - see below:  *//***************************************************************************** * * Sunclock version 3.xx by Jean-Pierre Demailly * * Is derived from the previous versions whose notices appear below. * See CHANGES for more explanation on the (quite numerous changes and * improvements). Version 3.xx is now published under the GPL. *//***************************************************************************** * * Sun clock.  X11 version by John Mackin. * * This program was derived from, and is still in part identical with, the * Suntools Sun clock program whose author's comment appears immediately * below.  Please preserve both notices. * * The X11R3/4 version of this program was written by John Mackin, at the * Basser Department of Computer Science, University of Sydney, Sydney, * New South Wales, Australia; <john@cs.su.oz.AU>.  This program, like * the one it was derived from, is in the public domain: `Love is the * law, love under will.' *//*****************************************************************************        Sun clock        Designed and implemented by John Walker in November of 1988.        Version for the Sun Workstation.    The algorithm used to calculate the position of the Sun is given in    Chapter 18 of:    "Astronomical  Formulae for Calculators" by Jean Meeus, Third Edition,    Richmond: Willmann-Bell, 1985.  This book can be obtained from:       Willmann-Bell       P.O. Box 35025       Richmond, VA  23235       USA       Phone: (804) 320-7016    This program was written by:       John Walker       Autodesk, Inc.       2320 Marinship Way       Sausalito, CA  94965       USA       Fax:   (415) 389-9418       Voice: (415) 332-2344 Ext. 2829       Usenet: {sun,well,uunet}!acad!kelvin           or: kelvin@acad.uu.net    modified for interactive maps by        Stephen Martin        Fujitsu Systems Business of Canada        smartin@fujitsu.ca    This  program is in the public domain: "Do what thou wilt shall be the    whole of the law".  I'd appreciate  receiving  any  bug  fixes  and/or    enhancements,  which  I'll  incorporate  in  future  versions  of  the    program.  Please leave the original attribution information intact  so    that credit and blame may be properly apportioned.*/#include <time.h>#include <math.h>#include "nxsunclock.h"/*  JDATE  --  Convert internal GMT date and time to Julian day	       and fraction.  */longjdate(t)     struct tm *t;{    long c, m, y;    y = t->tm_year + 1900;    m = t->tm_mon + 1;    if (m > 2)	m = m - 3;    else {	m = m + 9;	y--;    }    c = y / 100L;		/* Compute century */    y -= 100L * c;    return t->tm_mday + (c * 146097L) / 4 + (y * 1461L) / 4 +	(m * 153L + 2) / 5 + 1721119L;}/* JTIME --    Convert internal GMT  date  and	time  to  astronomical	       Julian  time  (i.e.   Julian  date  plus  day fraction,	       expressed as a double).	*/doublejtime(t)     struct tm *t;{#ifdef NOTUSED    long val = t->tm_sec + (60L * (t->tm_min + 60L * t->tm_hour));    double ret = (((double) (jdate(t) + val)) - 0.5) / 86400.0;    return (ret);#endif    return ((jdate(t) - 0.5) +	    (((long) t->tm_sec) +	     60L * (t->tm_min + 60L * t->tm_hour)) / 86400.0);}/*  KEPLER  --	Solve the equation of Kepler.  */doublekepler(m, ecc)     double m, ecc;{    double e, delta;#define EPSILON 1E-6    e = m = dtr(m);    do {	delta = e - ecc * sin(e) - m;	e -= delta / (1 - ecc * cos(e));    } while (abs(delta) > EPSILON);    return e;}/*  SUNPOS  --	Calculate position of the Sun.	JD is the Julian  date		of  the  instant for which the position is desired and		APPARENT should be nonzero if  the  apparent  position		(corrected  for  nutation  and aberration) is desired.                The Sun's co-ordinates are returned  in  RA  and  DEC,		both  specified  in degrees (divide RA by 15 to obtain		hours).  The radius vector to the Sun in  astronomical                units  is returned in RV and the Sun's longitude (true		or apparent, as desired) is  returned  as  degrees  in		SLONG.	*/voidsunpos(jd, apparent, ra, dec, rv, slong)     double jd;     int apparent;     double *ra, *dec, *rv, *slong;{    double t, t2, t3, l, m, e, ea, v, theta, omega, eps;    /* Time, in Julian centuries of 36525 ephemeris days,       measured from the epoch 1900 January 0.5 ET. */    t = (jd - 2415020.0) / 36525.0;    t2 = t * t;    t3 = t2 * t;    /* Geometric mean longitude of the Sun, referred to the       mean equinox of the date. */    l = fixangle(279.69668 + 36000.76892 * t + 0.0003025 * t2);    /* Sun's mean anomaly. */    m = fixangle(358.47583 + 35999.04975 * t - 0.000150 * t2 -		 0.0000033 * t3);    /* Eccentricity of the Earth's orbit. */    e = 0.01675104 - 0.0000418 * t - 0.000000126 * t2;    /* Eccentric anomaly. */    ea = kepler(m, e);    /* True anomaly */    //opera = sqrt((1 + e) / (1 - e));    //operb = tan(ea / 2);    //operc = rtd(opera * operb);    //v = fixangle(2 * operc);    v = fixangle(2 * rtd(atan(sqrt((1 + e) / (1 - e)) * tan(ea / 2))));    /* Sun's true longitude. */    theta = l + v - m;    /* Obliquity of the ecliptic. */    eps = 23.452294 - 0.0130125 * t - 0.00000164 * t2 + 0.000000503 * t3;    /* Corrections for Sun's apparent longitude, if desired. */    if (apparent) {	omega = fixangle(259.18 - 1934.142 * t);	theta = theta - 0.00569 - 0.00479 * sin(dtr(omega));	eps += 0.00256 * cos(dtr(omega));    }    /* Return Sun's longitude and radius vector */    *slong = theta;    *rv = (1.0000002 * (1 - e * e)) / (1 + e * cos(dtr(v)));    /* Determine solar co-ordinates. */    //opera = cos(dtr(eps)) * sin(dtr(theta));    //operb = cos(dtr(theta));    //operc = rtd(atan2(opera, operb));    //*ra = fixangle(operc);    *ra =	fixangle(rtd		 (atan2(cos(dtr(eps)) * sin(dtr(theta)), cos(dtr(theta)))));    *dec = rtd(asin(sin(dtr(eps)) * sin(dtr(theta))));}/*  GMST  --  Calculate Greenwich Mean Siderial Time for a given	      instant expressed as a Julian date and fraction.	*/doublegmst(jd)     double jd;{    double t, theta0;    /* Time, in Julian centuries of 36525 ephemeris days,       measured from the epoch 1900 January 0.5 ET. */    t = ((floor(jd + 0.5) - 0.5) - 2415020.0) / 36525.0;    theta0 = 6.6460656 + 2400.051262 * t + 0.00002581 * t * t;    t = (jd + 0.5) - (floor(jd + 0.5));    theta0 += (t * 24.0) * 1.002737908;    theta0 = (theta0 - 24.0 * (floor(theta0 / 24.0)));    return theta0;}